Runlevels ========= Finit supports runlevels, but unlike other init systems runlevels are declared per service/run/task/sysv command. When booting up a system Finit pass through three phases: 1. Setting up the console, parsing any command line options, and other housekeeping tasks like mounting all filesystems, and calling `fsck` 2. Starting all run/task/services in runlevel S, then waiting for all services to have started, and all run/tasks to have completed 3. Go to runlevel 2, or whatever the user has set in the configuration Available runlevels: - ` S`: bootStrap - ` 1`: Single user mode - `2-5`: traditional multi-user mode - ` 6`: reboot - `7-9`: multi-user mode (extra) - ` 0`: shutdown Runlevel S (bootStrap), is for tasks supposed to run once at boot, and services like `syslogd`, which need to start early and run throughout the lifetime of your system. Example: task console-setup { runlevel = "S" command = "/lib/console-setup/console-setup.sh" } service rsyslogd { runlevel = "S12345" envfile = "-/etc/default/rsyslog" command = "rsyslogd -n $RSYSLOGD_ARGS" } When bootstrap has completed, Finit moves to runlevel 2. This can be changed in `/etc/finit.conf` with `runlevel = N`, or by a script running in runlevel S that calls, e.g., `initctl runlevel 9`. The latter is useful if startup scripts detect problems outside of Finit's control, e.g., critical services/devices missing or hardware problems. Each runlevel must be allowed to "complete". Meaning, all services in runlevel S must have started and all run/tasks have been started and collected (exited). Finit waits 120 seconds for all run/tasks in S to complete before proceeding to 2. Finit first stops everything that is not allowed to run in 2, and then brings up networking. Networking is expected to be available in all runlevels except: S, 1 (single user level), 6, and 0. Networking is enabled either by `network = "script"`, or if you have an `/etc/network/interfaces` file, Finit calls `ifup -a` -- at the very least the loopback interface is brought up. > [!NOTE] > When moving from runlevel S to 2, all run/task/services that were > constrained to runlevel S only are dropped from bookkeeping. So when > reaching the prompt, `initctl` will not show these run/tasks. This is > a safety mechanism to prevent bootstrap-only tasks from accidentally > being run again. E.g., `console-setup.sh` above. Runlevel Configuration ---------------------- **Syntax:** `runlevel = N` The system runlevel to go to after bootstrap (S) has completed. `N` is the runlevel number 0-9, where 6 is reserved for reboot and 0 for halt. Completed in this context means all services have been started and all run/tasks have been started and collected. It is recommended to keep runlevel 1 as single-user mode, because Finit disables networking in this mode. *Default:* 2 > [!NOTE] > Only read and executed in runlevel S (bootstrap). Networking ---------- **Syntax:** `network = "PATH"` Script or program to bring up networking, with optional arguments. Deprecated. We recommend using dedicated task/run blocks per runlevel, or `/etc/network/interfaces` if you have a system with `ifupdown`, like Debian, Ubuntu, Linux Mint, or an embedded BusyBox system. > [!NOTE] > Only read and executed in runlevel S (bootstrap). System Hostname --------------- **Syntax:** `hostname = "NAME"` Set system hostname to NAME, unless `/etc/hostname` exists in which case the contents of that file is used. Deprecated. We recommend using `/etc/hostname` instead. > [!NOTE] > Only read and executed in runlevel S (bootstrap). Kernel Modules -------------- **Syntax:** `modules = { "MODULE [ARGS]", ... }`, alias `mod` Load kernel modules, each with optional arguments. Similar to the `insmod` command line tool. modules = { "button", "evdev", "softdog" } > [!NOTE] > A list cannot hold comments; the lexer reads the entries after a `#` > regardless. Put commented-out candidates above the list. Deprecated, there is both a `modules-load.so` and a `modprobe.so` plugin that can handle module loading better. The former supports loading from `/etc/modules-load.d/`, the latter uses kernel modinfo to automatically load (or coldplug) every required module. Hotplug module loading is handled by [keventd](../keventd.md), the built-in device manager. On systems using the hotplug plugin with BusyBox mdev instead, add to `/etc/mdev.conf`: $MODALIAS=.* root:root 0660 @modprobe -b "$MODALIAS" > [!NOTE] > Only read and executed in runlevel S (bootstrap). Resource Limits --------------- **Syntax:** `rlimit { RESOURCE = LIMIT }`, with `soft.` or `hard.` prefix Set the hard or soft limit for a resource, or both if the prefix is omitted. `RESOURCE` is the lower-case `RLIMIT_` string constants from `setrlimit(2)`, without prefix. E.g. to set `RLIMIT_CPU`, use `cpu`. LIMIT is an integer that depends on the resource being modified, see [setrlimit(2)](https://man7.org/linux/man-pages/man2/setrlimit.2.html), or the kernel `/proc/PID/limits` file, for details. Finit versions before v3.1 used `infinity` for `unlimited`, which is still supported, albeit deprecated. rlimit { hard.as = 8388608 # no more than 8MB of address space soft.core = unlimited # core dumps may be arbitrarily large cpu = 10 # soft & hard = 10 sec } `rlimit` can be set globally, in `/etc/finit.conf`, or locally per each `/etc/finit.d/*.conf` read. I.e., a set of task/run/service blocks can share the same rlimits if they are in the same .conf. For a service with [`pam`](pam.md), `pam_limits` runs after these limits are applied, so `limits.conf` has the last word. Miscellaneous Settings ---------------------- **Syntax:** `reboot-delay = 0-60` Optional delay at reboot (or shutdown or halt) to allow kernel filesystem threads to complete after calling `sync(2)` before rebooting. This applies primarily to filesystems that do not have a reboot notifier implemented. At the point of writing, the only known filesystems affected are: ubifs, jffs2. *Default:* 0 (disabled) When enabled (non-zero), this delay runs after file systems have been unmounted and the root filesystem has been remounted read-only, and sync(2) has been called, twice. > "On Linux, sync is only guaranteed to schedule the dirty blocks for > writing; it can actually take a short time before all the blocks are > finally written. **Syntax:** `reboot-watchdog = true|false` Controls whether the system should reboot via the watchdog timer (WDT) or directly via the SoC/kernel. When enabled, Finit will: 1. Send `SIGPWR` to the registered watchdog daemon before shutdown 2. Send `SIGTERM` to the watchdog daemon and wait up to 10 seconds for the watchdog to trigger a hardware reset When disabled (default), Finit skips the watchdog reboot logic and calls the kernel's `reboot(2)` syscall directly for a clean SoC reboot. *Default:* off (reboot via SoC) > [!NOTE] > This setting only affects reboots. The watchdog daemon will still > run and monitor the system during normal operation.